Molecular Basis for Nucleotide Conservation at the Ends of the Dengue Virus Genome

• DOI: 10.1371/journal.ppat.1002912
• Publication Date: 2012-09-15T01:00:11Z
• Authors: Barbara Selisko; Supanee Potisopon; Rym Agred; Stéphane Priet; Isabelle Varlet; Yann Thillier; Corinne Sallamand; Françoise Debart; Jean-Jacques Vasseur; Bruno Canard
• Keywords: Primer (cosmetics)

The dengue virus (DV) is an important human pathogen from the Flavivirus genus, whose genome- and antigenome RNAs start with strictly conserved sequence pppAG. RNA-dependent RNA polymerase (RdRp), a product of NS5 gene, initiates synthesis de novo, i.e., without use pre-existing primer. Very little known about mechanism this novo initiation how conservation starting adenosine achieved. domain NS5PolDV NS5, upon on viral templates, synthesizes mainly dinucleotide primers that are then elongated in processive manner. We show here contains specific priming site for 5′-triphosphate as first transcribed nucleotide. Remarkably, absence any template enzyme able to selectively synthesize pppAG when Mn2+ present catalytic ion. T794 A799 loop essential provides at least part ATP-specific site. H798 residue central importance step. In addition ATP selection, ensures 5′-adenosine by strongly discriminating against templates containing erroneous 3′-end nucleotide presence Mg2+. Mn2+, remarkably generate elongate correct primer these templates. This can be regarded genomic/antigenomic end repair mechanism. These conservational mechanisms, mediated alone, may extend other families having RdRps initiating novo.